Dual-Lane Roundabouts Geometric Design for Optimum Design Consistency and Operation

Dual-lane roundabouts successfully controlling traffic because of their slower entry speeds and fewer conflict points compared to conventional intersections. Operational evaluations of dual-lane roundabouts depend on the average delay at each roundabout entry, and the delay of each entry depends on the entry capacity. An optimization model is developed in this thesis for dual-lane right-angle and skewed-angle roundabouts, which determines the design elements of the roundabout based on design consistency and the least average intersection delay. The design element includes vehicle radii for through, left, and right turn traffic paths. The design consistency of an individual path is considered by minimizing the relative speed difference along each vehicle path for all approaches. Operational analysis gives an estimation of the capacity and level of service in terms of queue length and delay. These models use site conditions as inputs and prove the feasibility of the design.